Mask



FIG. 1 is a top view of the disclosed mask;

FIG. 2 is a side view of the disclosed mask;

FIG. 3 is a rear view of the disclosed mask;

FIG. 4 is a front view of the disclosed mask;

FIG. 5 is a bottom view of the disclosed mask, the broken lines in FIG. 5 are included for the purpose of illustrating environmental structure of the inhaler that forms no part of the claimed design; and,

FIG. 6 is a perspective view of the disclosed mask. 

The ornamental design for a mask, as shown and described. 